Question

I’m going to filter some countries from <select id="country" ...> according their value. I’ve tried grep and filter in jQuery but not successful. Just for one element it’s working ok.
I don’t know how to make correct array in jQuery.

 jQuery.noConflict();
 function change_country(seldd) {     
    var look_for_id=''; var opt_id=[];
 jQuery('#countries').html("");
 jQuery("#countries").append("<option value='0'>-Country-</option>");
    if(seldd.value=='0') { look_for_id='N'; }   
    if(seldd.value=='1'){ look_for_id='Y';  opt_id=jQuery.filter($("#country option").val(["1,   2, 3, 4"])); }  
    if(seldd.value=='2'){ look_for_id='Y';  opt_id=jQuery.grep(['5', '6', '7', '8']); }  
    if(look_for_id=='Y') {
 jQuery("#country option[value='"+opt_id+"']").each(function() {
 jQuery("#countries").append("<option   value='"+jQuery(this).val()+"'>"+jQuery(this).text()+"</option>");
  });
 } else {
 jQuery("#country option").each(function() {
 jQuery("#countries").append("<option  value='"+jQuery(this).val()+"'>"+jQuery(this).text()+"</option>");
    });
  }  
 }

 <div>      
<select id="region" id="srv_type" onchange="change_fruit(this)" >
  <option value="0" selected="selected">Регион</option>
  <option value="1">Asia</option>
  <option value="2">Europe</option>
</select>  </div> 

<div style="display:none;" >   
<select id="country" name="country" class="inputbox">
   <option value="" selected="selected">Страна</option>
   <option value="1" >Indonesia</option>
   <option value="2">Thailand</option>
   <option value="3">Singapore</option>
   <option value="4">Malaysia</option>
   <option value="5">Greece</option>
   <option value="6">Italy</option>
   <option value="7">Monaco</option>
   <option value="8">Spain</option>
</select>
</div>
<select name="countries" id="countries">
   <option value="0">-Country-</option>
</select>

Answer 1

a jquery array is the same as a javascript array.e.g.

thing = [];

or

thing = new Array();

If you add things to your array e.g.

countries = ['UK','USA','etc'];

you can the loop though them using jquery .each or a for loop. You could also have an array of arrays e.g.

thing = [['UK','Europe'],['USA','North America']];

then loop through the main array and access the other elements via their index.

thing[0][0] would output UK.

Just did a quick google and this might help you:

http://www.hunlock.com/blogs/Mastering_Javascript_Arrays

It shows some of the other things you can do with arrays